Long carbon chain quaternary ammonium salt is a cation surfactant which has been widely applied as a shampoo conditioner in hair cosmetics. Long carbon chain quaternary ammonium salt can reduce electrostatic accumulation, maintain hair smoothness and improve hair combability. However, long carbon chain quaternary ammonium salt has apparent demerit, such as strong irritation, poor compatibility with anions, which limit its applications. The reason for wide use of long carbon chain quaternary ammonium salt lies in that the quaternary ammonium salt in its structure has positively charged nitrogen atoms, which function as electrostatic resistant. Additionally, long carbon chains such as fatty acid chains, polymer chains and the like have good affinity and thus can be attached to hair after washing. Therefore, long carbon chain quaternary ammonium salt exhibits the advantages of good dry combability, wet combability, electrostatic resistance as well as twist resistance. The length of the carbon chain would affect the performance of long carbon chain quaternary ammonium salt to a great extent. Longer carbon chain would provide more excellent performance and its affinity with the hair would be stronger. Meanwhile, the longer the carbon chain, the lower and milder the toxicity of its cells. However, quaternary ammonium salt would deposit when combining with anions, making the formula unstable. In order to reduce accumulation of the electric charges and make quaternary ammonium more compatible with anions, it is generally required to improve its structure, for example, to connect an EO (ethylene oxide) or a PO (propylene oxide) chain thereto. Another option is to modify its structure such as make it into an ampholytic surfactant, while this option would deteriorate the performance of quaternary ammonium salt.
Alkyl phosphate ester is a mild anion surfactant and has widely been applied in cleansing products such as cleansing facial milk, shower bath and the like.
The long carbon chain quaternary ammonium phosphate ester obtained by connecting the two structures described above is a special ampholytic surfactant having both structures of quaternary ammonium salt and phosphate ester. In addition to exhibiting surface activities of an ampholytic surfactant, said long carbon chain quaternary ammonium phosphate ester exhibits some other special properties, such as bacteriostasis. U.S. Pat. Nos. 4,243,602, 4,283,542 and 5,286,719 disclose methods for synthesizing the long carbon chain quaternary ammonium phosphate ester, its use as an antibacterial agent, and call it a biomimetic phospholipid.
The uses of long carbon chain quaternary ammonium phosphate ester as a surfactant in personal care and household products are widely disclosed in prior art. However, due to existence of the structure of phosphate ester, which is generally thought as affecting the conditioning properties of quaternary ammonium salt, the use of long carbon chain quaternary ammonium phosphate ester as a hair conditioner or a hair care agent has not been disclosed. Let alone the properties and use of the quaternary ammonium phosphate ester having an extremely long carbon chain structure